The present invention relates to knee support devices, and more particularly to a dynamic patellar brace or splinting device intended to stabilize the patella to prevent patellar subluxation during all normal degrees of knee flexion and motion.
It is well-known that loosely ligamented individuals, as well as individuals with certain peculiar anatomic features of certain components of the knee, frequently develop various pathological problems with their knees, particularly when these individuals are active in physically strenuous activities, such as athletic activities. The most commonly occurring problems relate to stretching or tearing of the various knee ligaments, injury to the cartilage (meniscal) and articular surfaces of the knee joint, and fractures. Patellar subluxation or abnormal and undesirable movement of the patella, laterally, relative to its normal up and down movement in the vertical track defined by the trochlea can precipitate the onset of chondromalacia or aggravate existing chondromalacia of the patella, as well as cause diagnostic problems of the knee.
Subluxation of the patella can be caused by certain developmental abnormalities of the skeletal components of the knee and/or the presence of musculaligamentous laxity or dysplasia. The patella may leave its normal, vertical tracking groove as a result of abnormal vector forces and/or by passive lateral or rotary forces. The abrupt abnormal lateral displacement of the patella from its groove during any weight bearing activity (such as running, stair climbing, etc.) frequently results in immediate, temporary disability (such as buckling of the knee), causing a subjective sensation in the knee similar to that caused by other unrelated pathological conditions within the knee.
The sensation of pain and/or imminent buckling of the knee results in apprehension and restriction of certain weight bearing activities such as athletic endeavors. The resultant increased abnormal traction forces on the peripatellar soft tissues frequently lead to inflammatory changes of the retinaculae, patellar ligament and/or tendon (tendinitis).
Furthermore, the repetitive, abnormal lateral excursions which cause abnormal shearing forces, frequently lead to early, accelerated and progressive degenerative changes (chondromalacia) of the patella and femoral condyles.
As noted above, problems peculiar to the patella compromise only a portion of all common physiological problems of the knee and several, unrelated or partially related problems may occur simultaneously, particularly in individuals having loose ligaments or when engaged in relatively strenuous activities involving the knee. Physicians generally, and orthopedic surgeons in particular, have only recently begun to fully appreciate the frequency and importance of patellar subluxation in the context of overall knee problems. Accordingly, the diagnosis of patellar subluxation may be difficult to ascertain using conventional techniques, especially because other problems with the knee frequently cause subjective symptoms similar to those of subluxation of the patella.
Not only may the proper diagnosis of patellar subluxation, particularly in its milder form, be difficult using conventional techniques, but even when properly diagnosed, the preferred treatment may be somewhat limited. For example, young children still in the active bone growth phase of life frequently are relatively loosely ligamented and suffer from various degrees of patellar subluxation. However, it is well recognized that it is preferable to avoid or delay corrective surgery for such individuals, if at all possible, until such individuals reach a more physiologically opportune age when their growth plates have closed.
Others have devoted attention and proposed various knee braces and supports directed to general problems of the knee. For example, Spiro, U.S. Pat. No. 3,473,527; Lehman, U.S. Pat. No. 3,804,084, and Moore, U.S. Pat. No. 3,853,123, have proposed various knee support, brace, and knee splinting devices intended to restrain the knee to prevent normal knee flexion or movement. Such devices are directed, generally, to the problem of immobilizing the knee as a whole, and do not provide dynamic patellar bracing during normal knee flexion and extension. Nirschl, U.S. Pat. No. 3,926,186 and Stromgern, U.S. Pat. No. 3,945,046, propose other muscular and flexible knee supports. Nirschl's apparatus, however, is not designed to provide medial-lateral stabilization of the patella, and is inherently incapable of performing a dynamic bracing function for the patella. Stromgern's apparatus, on the other hand, is not concerned with patellar stabilization, but instead is directed to the general problem of providing stability to the medial knee ligament complex.
Detty, U.S. Pat. No. 4,084,585 discloses a simple knee sleeve device which includes a pad and which is capable of providing limited, static patellar bracing when the knee is passive, i.e., not in motion or when in a single position or a narrow range of positions.